The subject invention pertains to polymeric fiber webs with an improved binding composition and load bearing at elevated temperatures. More specifically, the invention pertains to non-woven polymeric fiber webs using an improved curable composition comprising an amine salt of an inorganic acid. An aldehyde or ketone is added to the salt to form a composition which upon curing is capable of forming a water-insoluble polymer. Once applied to the polymer fibers, the binding composition is cured.
Nonwoven webs comprised of polymeric fibers have a variety of applications. The applications can range from prepeg laminates; polishing or abrasive pads; separators for alkali battery cells; laminated materials for electrical circuit boards; filters, both for gas and liquids; diapers; towels; wipes; industrial and medical garments; foot covers; sterilization wraps, etc.
In many of the applications, the polymeric fibers of the nonwoven web must exhibit good physical properties such as chemical resistance and heat resistance. The nonwoven web is many times used in a hazardous environment, and therefore demands are placed on its construction. This would include not only the polymeric fibers, but also the binder used in the nonwoven web. Many different binders have been used in the past for nonwoven polymeric fiber webs.
For example, in U.S. Pat. No. 7,026,033, a heat resistant nonwoven web comprised of organic synthetic fibers also uses an organic resin binder. The binder is selected from an epoxy resin, phenol resin, melamine resin, formaldehyde resin and fluropolymer resin.
U.S. Pat. No. 7,534,163 describes a non-woven fabric for a polishing pad used to polish semi-conductors. The fibrous component of the pad can be selected among polyester, polypropylene, polyamide, acrylic, polyethylene and cellulosic materials. The binder used for the pad includes resins of polyurethanes, polyacrylates, polystyrenes, polyamides, polycarbonates and epoxies.
Economies without sacrificing physical properties is always a concern in preparing such non-woven polymeric fiber webs. The industry continuously searches for non-woven polymeric fiber webs that can provide the physical properties needed to achieve the required performance, but which offer an economic advantage.
Accordingly, in one aspect the present invention provides a novel nonwoven polymeric fiber web comprised of a non-phenol-formaldehyde binder.
Another aspect of the invention provides a novel nonwoven polymeric fiber web with a binder which provides advantageous flow properties, the possibility of lower binder usage, the possibility of overall lower energy consumption, increased sustainability of the raw materials utilized in the formation of the binder, considerable reduction in the use of petroleum based ingredients, elimination of process corrosion, elimination of interference in the process by a silicone, and improved overall economics.
Still another aspect of the present invention is to provide a nonwoven polymeric fiber web which uses a suitable binder having improved economics, while also enjoying improved physical properties, including chemical resistance and heat resistance.
These and other aspects of the present invention will become apparent to the skilled artisan upon a review of the following description and the claims appended hereto.